Admin CSV import rejects valid .csv files on Windows (MIME type check)

Bug Report

Description

The product import CSV upload in the admin dashboard rejects valid .csv files on Windows machines where Microsoft Excel is installed. The error displayed is:

'{filename}.csv' is not a supported file type. Supported file types are: .csv.

Root Cause

The UploadImport component validates files by checking file.type (MIME type) against ["text/csv"]:

// packages/admin/dashboard/src/routes/products/product-import/components/upload-import.tsx
const SUPPORTED_FORMATS = ["text/csv"]

const hasInvalidFiles = (fileList: FileType[]) => {
  const invalidFile = fileList.find(
    (f) => !SUPPORTED_FORMATS.includes(f.file.type)
  )
  // ...
}

On Windows with Excel installed, the registry key HKEY_CLASSES_ROOT\.csv has Content Type set to application/vnd.ms-excel instead of text/csv. The browser reports this system-level MIME type, causing the validation to fail despite the file having a valid .csv extension.

Suggested Fix

Check the file extension instead of the MIME type, since MIME type detection is unreliable across operating systems:

const hasInvalidFiles = (fileList: FileType[]) => {
  const invalidFile = fileList.find(
    (f) => !f.file.name.toLowerCase().endsWith(".csv")
  )
  // ...
}

Alternatively, expand SUPPORTED_FORMATS to include common CSV MIME types:

const SUPPORTED_FORMATS = ["text/csv", "application/vnd.ms-excel", "application/csv", "text/plain"]

Environment

• Medusa version: 2.15.2
• OS: Windows 11 with Microsoft Excel installed
• Browsers affected: All (Chrome, Edge, Firefox) — MIME type comes from the OS registry

Steps to Reproduce

1. Install Microsoft Excel on a Windows machine (or have it pre-installed)
2. Open the Medusa admin dashboard
3. Navigate to Products → Import
4. Try to upload any valid .csv file
5. Observe the error: "not a supported file type"

Workaround

Users can fix the Windows registry to reassign the CSV MIME type:

Set-ItemProperty -Path "Registry::HKEY_CLASSES_ROOT\.csv" -Name "Content Type" -Value "text/csv"

Then restart the browser.